The invention relates to a device for affixing adhesive labels to goods packages, according to the precharacterising part of claim 1.
From printed publication DE 195 31 426 A1, a device for affixing adhesive labels to goods packages according to the enclosed FIG. 4 is known. It comprises a cylinder 1 in which a piston 2 is movably arranged. On the jacket of cylinder 1, connections 3 and 4 are arranged which, by alternative connection to a compressed-air source and/or negative-pressure source, cause the piston to move in the cylinder. Movement of the piston 2 is transmitted to a stamp 6 via a bolt 9 and a piston rod 5, said stamp 6 protruding from the cylinder. Adhesive labels (not shown in FIG. 4, but known from the above-named printed publication) are fed to the stamp 6. Having been fed to the stamp 6, said adhesive labels are then affixed to goods packages 50 by movement of the piston 2 and the stamp 6.
DE 195 31 426 A1 further discloses the special embodiment of the cylinder 1 shown in the enclosed FIG. 5. According to this embodiment, the cylinder 1, at its end facing away from the stamp, comprises a pneumatic damping unit 10 which closes off the cylinder in that region. The damping unit comprises a pneumatic cylinder 11 in which a damping piston 12 is guided, whose piston rod 13 protrudes into the inside of the cylinder 1.
On its surface, the piston 2 comprises a permanent magnet 7 which pushes against a ferromagnetic counter ring 8 when it has reached a minimum distance from the pneumatic damping unit 10, i.e. in a first dead centre position. The connection 3 is located on the jacket of the cylinder 1 in a region between the counter ring 8 and the pneumatic damping unit 10. Since the movement of the piston 2 is limited by the counter ring 8, i.e. by the first dead centre position defined by it, at no time during operation of the device is the connection 3 closed off by the wall of the piston 2.
In order to move the piston 2 into the first dead centre position, negative pressure is built up in the interior of the cylinder 1, above the piston 2, by way of the connection 3. This negative pressure generates an accelerating force acting on the piston 2. This accelerating force must be quite substantial if the required labelling speed or dynamics of 140 goods packages per minute is to be achieved. Furthermore, this accelerating force and the resulting speed of the piston 2 must be quickly and effectively decelerated near the turning points, i.e. dead centre positions within the cylinder. In the state of the art this happens by way of two types of damping measures.
Firstly, the surface of the piston 2 hits the piston 13 of the damping unit 10 which provides a degree of resistance to it. Secondly, shortly before the piston reaches the first dead centre position, the negative pressure is switched off, and instead, a blast of compressed air is introduced to the interior of the cylinder 1, by way of the connection 3. Said blast of compressed air also acts on the surface of the piston 2, in this way providing additional deceleration of the piston 2.
As seen from FIG. 4, the described device is not only used for labelling goods packages 50 which are of the same height, but moreover it is also used for goods packages of differing heights. The pneumatic cylinder 10 according to FIG. 5, which cylinder has been described above, requires individual adjustment for particular standard heights. Having been adjusted to a particular standard height, the device is then able to label packages with a certain tolerance range in the height of said packages. In the state of the art, resetting the device to goods packages of other standard heights requires an interruption in the labelling process and manipulation of the pneumatic damping unit 10.